1. Field of the Invention
The present invention relates to an apparatus for scanning a gyroscope, but more particularly the present invention relates to an apparatus for enlarging the scanning field of the gyroscope so as to improve target acquisition of an associated guided missile system.
2. Description of the Prior Art
Heretofore, various apparatuses and techniques have been advanced to improve the utility of gyroscopes in target searching, target acquisition and target tracking especially in guided missile systems. One such technique has been to control the nutation of a gyroscope so as to permit circular or elliptical scan patterns for target seeking purposes. Here, a fixed amplitude excitation at the natural frequency of a spinning mass portion of the gyroscope is introduced to cause nutation in the pitch and yaw axes of the gyroscope. In the absence of a negative rate feedback signal, maximum circular nutation is obtained. Nutation control is obtained by comparing the amplitudes of rate feedback and nutation command signals in a control circuit. The foregoing signals are used to generate torque control signals to cause the aforementioned spinning mass portion of the gyroscope to nutate.
The present invention is contemplated for use with gyroscopes that generate a cage coil signal consisting of an amplitude and phase modulated waveform wherein the frequency of the carrier portion is the same as the inertial spin rate of a rotor magnet, i.e., spinning mass portion of the gyroscope. With the foregoing in mind, the previously mentioned technique does not include scanning by phase shifting the cage coil signal as a function of its amplitude and then driving a precession coil of the gyroscope with a constant amplitude signal which is phase-locked to the phase shifted cage coil signal. Consequently, there is a need in the prior art to configure an apparatus for scanning a rotating gyroscope using the foregoing technique.
As additional background, target seekers using various types of sensors, including radiation types for generating error signals for precessing a particular gyroscope to align its axis with a desired target, have been disclosed in the prior art. Also, at least one technique for generating scanning patterns other than circular and elliptical, e.g., conical, is disclosed.
The prior art and background, as indicated hereinabove, include some advances in gyroscope scanning apparatuses and techniques; however, insofar as can be determined, no prior art apparatus or technique incorporates all of the features and advantages of the present invention.